Re: My new heads are killing me need help
[Re: 70dusterjohn]
#2538726
08/19/18 10:30 PM
08/19/18 10:30 PM
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Joined: Jan 2003
Posts: 20,335 Park Forest, IL
slantzilla
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 20,335
Park Forest, IL
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Any chance the relief is stuck in the fuel pump? I had that happen once and it would never show a symptom until you tried to launch the car at the track.
"Everybody funny, now you funny too."
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Re: My new heads are killing me need help
[Re: B3422W5]
#2538741
08/19/18 10:57 PM
08/19/18 10:57 PM
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Joined: Feb 2005
Posts: 4,333 Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,333
Prospect, PA
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* Jet for MPH. * Squirters & pump cams for 60'
Be careful so one doesn't overlap the other. (i.e.: too much jet can mask a need for bigger squirters and/or a bigger (longer squirting) pump cam.
Smaller squirters will increase the duration of the squirt and bigger squirters will shorten the duration of a given pump cam. You don't want the squirt any longer or shorter than necessary because it will mess up the A/F ratio of the main metering system (jets). Yep. All that stuff contributes to optimal ET’s. But his car is off 8 tenths or more. I'm with you. His problem is not jets and squirters. How many mph is it off? I would be looking for something bigger that was touched when in the motor.
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Re: My new heads are killing me need help
[Re: 70dusterjohn]
#2538933
08/20/18 11:37 AM
08/20/18 11:37 AM
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Joined: Jan 2003
Posts: 14,539 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,539
So. Burlington, Vt.
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Have It dynoed........ figure out if it’s the motor combo, an accessory(fuel pump, ign, carb), or something else in the car(converter, wiring, etc).
If the motor makes the expected power, you can rule that out and focus on the other stuff.
I’d bring my carb and ign box with me if you get it tested.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: My new heads are killing me need help
[Re: 70dusterjohn]
#2539308
08/20/18 10:50 PM
08/20/18 10:50 PM
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Joined: Mar 2008
Posts: 5,746 Ontario, Canada
Dodgem
master
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master
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
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Your sure the mark on the balancer is right?? leak down and compression test maybe it is hitting the valves? so does it just lie down right off the line? Valves are not marking pistons. no missing just flat??
Last edited by Dodgem; 08/20/18 10:56 PM.
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Re: My new heads are killing me need help
[Re: 70dusterjohn]
#2539971
08/22/18 12:17 PM
08/22/18 12:17 PM
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Joined: Jan 2003
Posts: 14,539 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,539
So. Burlington, Vt.
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This is a good example of why if someone brings me a motor with the intent of me making a few changes to increase the power output....... it gets put on the dyno before being taken apart.
This does two things(for a drag application)..... -establishes a baseline number to work from. -helps determine if the “car” is running the et’s it should for the power the motor currently makes.
I’ve seen it go both ways before. -The car was slow, but the motor was doing exactly what it should...... so no changes were made to the motor......... and the customer diligently worked on the car and ultimately picked up over .5 ET without making any more power. -The car was slow...... and the motor was down a solid 50hp from what I was getting from very similar combos.
Of course, then there’s the situation where someone buys a motor that came with a dyno sheet, and the car hasn’t been running et’s or speeds representative of the dyno numbers are....... and they have spent thousands on fuel system upgrades, trans parts, converters, maybe some gears, etc....... all to no avail. Then we put it on the dyno and it’s down 50, 75, 100hp from what the dyno sheet that came with the motor shows......... and the car is going exactly as fast as it should, based on our numbers. It’s this scenario that lead me to start testing before any modifications begin....... to make sure everyone is on the same page right from the start.
The OP’s car is running way way off from what it should. It shouldn’t be that hard to come up with a realistic horsepower estimate for that combination of parts. If the motor makes within +/- 30hp of that figure....... you can leave the motor combo alone........ it’s not your problem. On the other hand, if it’s down 100hp....... better get it apart and start looking.
Obviously, you’d like to test at a dyno service that has a good history of cars running times/speeds that are in line with what’s expected based on the dyno numbers.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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